FSH beta subunit expression is regulated by GnRH, ovarian steroids and the peptide hormones activin and inhibin, but little is known about the regulation of FSH beta gene transcription. The first aim of this project is to validate a novel method for assessing FSH beta gene transcription by measuring pituitary FSH beta primary transcript by quantitative RT-PCR. The second aim of this proposal is to study the regulation of FSH beta transcription by GnRH. The regulation of FSH beta transcription after ovariectomy and by alterations in GnRH pulse amplitude and frequency will be explored. The third aim of this proposal is to study the regulation of FSH beta gene transcription by ovarian steroids, inhibin, and activin. The direct effect of steroids on the pituitary as well as the modulation of GnRH effects by steroids will be determined in GnRH deficient rats. Inhibin and activin bioactivity will be neutralized in intact rats in vivo by inhibin antiserum and the activin binding protein follistatin respectively and the effects on FSH beta transcription will be determined. This proposal will extend our understanding of the regulation of mammalian reproduction and may be applied to understanding of the mechanisms of fertility.